1. Field of the Invention
The present invention relates to an ice making method for producing ice in a vertical ice making machine comprising an ice making plate extending in the vertical direction.
2. Description of the Related Art
FIG. 8 shows the vicinity of an ice making plate in a conventional vertical ice making machine as disclosed in Japanese Utility Model Examined Publication No. H3-28280. A plurality of vertical ribs 2 are formed on the surface of an ice making plate 1 so as to extend in the vertical direction. Each vertical rib 2 is arranged at regular intervals in the lateral direction of the ice making plate 1. The plurality of vertical ribs 2 regulate the lateral size of the ice produced on the surface of the ice making plate 1. Further, a plurality of projecting portions 3 for facilitating dropping the ice are provided at regular intervals in the vertical direction between the adjacent vertical ribs 2. On the other hand, a cooling tube 4 is provided at the back surface of the ice making plate 1 as an evaporator for a refrigeration circuit (not shown).
During an ice making cycle with the above ice making machine, ice making water flows from a water distributor (not shown), provided at the upper part of the ice making plate 1, onto the surface of the ice making plate 1. The ice making water is cooled by the cooling tube 4, and substantially half-roll-shaped ice nuggets 6, as indicated by the solid lines in FIG. 9, are formed on the surface portion of the ice making plate 1, which corresponds to the opposite side of the cooling tube 4. A distance L1 from the cooling tube 4 to the edge face of the ice nugget 6, a pitch P1 of the cooling tube 4 etc., are determined such that each ice nugget 6 does not connect to the other ice nuggets 6 formed above and below it. Thus, the ice nuggets 6 are formed at regular intervals.
During a deicing cycle, deicing water at an ordinary temperature is distributed to the back surface of the ice making plate 1 and a portion of each ice nugget 6, which is in contact with the surface of the ice making plate 1, melts slightly, whereby, as indicated by the broken line of FIG. 9, the ice nugget 6 is supposed to slide downward by its own weight so as to ride over the projecting portion 3, to separate and fall from the ice making plate 1.
However, in the vertical ice making machine described above, since the ice nuggets 6 are formed at regular intervals so that each ice nugget 6 does not connect to the other ice nuggets 6 formed above and below it, a lot of space that is not utilized for ice making is formed, and the amount of ice making per unit surface area of the ice making plate 1 is reduced. Thus, there is a problem in that a large surface area for ice making is required.
Further, in the vertical ice making machine described above, since each ice nugget 6 formed individually falls from the ice making plate 1, there is a problem in that it takes a significant amount of time to drop all the ice nuggets 6 due to variations in melting of the contact portion of each nugget 6 with the ice making plate 1. Furthermore, as a result, there is a possibility of increasing the deicing water usage and the amount of the melting ice nuggets 6.